Effects of pH on aggregation kinetics of the repeat domain of a functional amyloid, Pmel17

Pfefferkorn, Candace M.; McGlinchey, Ryan P.; Lee, Jennifer C.

doi:10.1073/pnas.1006424107

Cited by 98 publications

(124 citation statements)

References 46 publications

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“…Human ␤ 2 -microglobulin and transthyretin form amyloid fibrils efficiently under acidic conditions in vitro (35)(36)(37). For functional amyloidogenic protein Pme17, a critical pH regime between 5 Ϯ 0.5 is required for fibril formation in a specific melanosome compartment (38).…”

Section: Discussionmentioning

confidence: 99%

Binding with Nucleic Acids or Glycosaminoglycans Converts Soluble Protein Oligomers to Amyloid

Domizio

Zhang

Stagg

et al. 2012

Journal of Biological Chemistry

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Ample evidence suggests that almost all polypeptides can either adopt a native structure (folded or intrinsically disordered) or form misfolded amyloid fibrils. Soluble protein oligomers exist as an intermediate between these two states, and their cytotoxicity has been implicated in the pathology of multiple human diseases. However, the mechanism by which soluble protein oligomers develop into insoluble amyloid fibrils is not clear, and investigation of this important issue is hindered by the unavailability of stable protein oligomers. Here, we have obtained stabilized protein oligomers generated from common native proteins. These oligomers exert strong cytotoxicity and display a common conformational structure shared with known protein oligomers. They are soluble and remain stable in solution. Intriguingly, the stabilized protein oligomers interact preferentially with both nucleic acids and glycosaminoglycans (GAG), which facilitates their rapid conversion into insoluble amyloid. Concomitantly, binding with nucleic acids or GAG strongly diminished the cytotoxicity of the protein oligomers. EGCG, a small molecule that was previously shown to directly bind to protein oligomers, effectively inhibits the conversion to amyloid. These results indicate that stabilized oligomers of common proteins display characteristics similar to those of disease-associated protein oligomers and represent immediate precursors of less toxic amyloid fibrils. Amyloid conversion is potently expedited by certain physiological factors, such as nucleic acids and GAGs. These findings concur with reports of cofactor involvement with disease-associated amyloid and shed light on potential means to interfere with the pathogenic properties of misfolded proteins.

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Section: Discussionmentioning

confidence: 99%

Binding with Nucleic Acids or Glycosaminoglycans Converts Soluble Protein Oligomers to Amyloid

Domizio

Zhang

Stagg

et al. 2012

Journal of Biological Chemistry

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“…While amyloids in humans are associated mostly with complex diseases, functional amyloids that serve a role in physiological processes such as melanin production and blood clotting have been reported (33)(34)(35)(36)(37)(38). In bacteria, amyloids function as a component of the extracellular matrix in biofilms of commensal organisms, such as spore-forming Bacillus subtilis and Pseudomonas fluorescens, or human pathogens, such as Mycobacterium tuberculosis, Salmonella enterica serovar Typhimurium, Citrobacter freundii, Enterobacter sakazakii, and Escherichia coli (39)(40)(41)(42)(43)(44)(45)(46).…”

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confidence: 99%

Epithelial Cells Augment Barrier Function via Activation of the Toll-Like Receptor 2/Phosphatidylinositol 3-Kinase Pathway upon Recognition of Salmonella enterica Serovar Typhimurium Curli Fibrils in the Gut

et al. 2013

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Curli fibrils, the best-characterized functional bacterial amyloids, are an important component of enterobacterial biofilms. We have previously shown that curli fibrils are recognized by the Toll-like receptor 2 (TLR2)/TLR1 heterodimer complex. Utilizing polarized T-84 cells, an intestinal epithelial cell line derived from colon carcinoma grown on semipermeable tissue culture inserts, we determined that infection with a Salmonella enterica serovar Typhimurium csgBA mutant, which does not express curli, resulted in an increase in intestinal barrier permeability and an increase in bacterial translocation compared to infection with curliated wild-type S. Typhimurium. When the TLR2 downstream signaling molecule phosphatidylinositol 3-kinase (PI3K) was blocked using wortmannin or LY294002, the difference in disruption of the intestinal epithelium and bacterial translocation was no longer observed. Additionally, disruption of polarized T-84 cells treated basolaterally with the TLR5 ligand flagellin was prevented when the polarized cells were simultaneously treated with the synthetic TLR2/TLR1 ligand Pam 3 CSK 4 or with purified curli fibrils in the apical compartment. Similar to in vitro observations, C57BL/6 mice infected with the csgBA mutant suffered increased disruption of the intestinal epithelium and therefore greater dissemination of the bacteria to the mesenteric lymph nodes than mice infected with wild-type S. Typhimurium. The differences in disruption of the intestinal epithelium and bacterial dissemination in the mice infected with csgBA mutant or wild-type S. Typhimurium were not apparent in TLR2-deficient mice. Overall, these studies report for the first time that activation of the TLR2/PI3K pathway by microbial amyloids plays a critical role in regulating the intestinal epithelial barrier as well as monitoring bacterial translocation during infection.

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“…Human β 2 -microglobulin and transthyretin form amyloid fibrils efficiently under acidic conditions in vitro 22,24,25 . For functional amyloidogenic protein Pme17, a critical pH regime between 5 +/-0.5 is required for fibril formation in a specific melanosome compartment 26 .…”

Section: Discussionmentioning

confidence: 99%

Rapid Generation of Amyloid from Native Proteins <em>In vitro</em>

Dorta‐Estremera

Cao

2013

JoVE

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Proteins carry out crucial tasks in organisms by exerting functions elicited from their specific three dimensional folds. Although the native structures of polypeptides fulfill many purposes, it is now recognized that most proteins can adopt an alternative assembly of beta-sheet rich amyloid. Insoluble amyloid fibrils are initially associated with multiple human ailments, but they are increasingly shown as functional players participating in various important cellular processes. In addition, amyloid deposited in patient tissues contains nonproteinaceous components, such as nucleic acids and glycosaminoglycans (GAGs). These cofactors can facilitate the formation of amyloid, resulting in the generation of different types of insoluble precipitates. By taking advantage of our understanding how proteins misfold via an intermediate stage of soluble amyloid precursor, we have devised a method to convert native proteins to amyloid fibrils in vitro. This approach allows one to prepare amyloid in large quantities, examine the properties of amyloid generated from specific proteins, and evaluate the structural changes accompanying the conversion. Video LinkThe video component of this article can be found at

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Effects of pH on aggregation kinetics of the repeat domain of a functional amyloid, Pmel17

Cited by 98 publications

References 46 publications

Binding with Nucleic Acids or Glycosaminoglycans Converts Soluble Protein Oligomers to Amyloid

Binding with Nucleic Acids or Glycosaminoglycans Converts Soluble Protein Oligomers to Amyloid

Epithelial Cells Augment Barrier Function via Activation of the Toll-Like Receptor 2/Phosphatidylinositol 3-Kinase Pathway upon Recognition of Salmonella enterica Serovar Typhimurium Curli Fibrils in the Gut

Rapid Generation of Amyloid from Native Proteins <em>In vitro</em>

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